As is well known, a contact lens is a tool that is mainly used to treat a disease called “ametropia”. In addition, since the contact lens requires safety, it is dealt with as a medical tool. Thus, when a contact lens to be purchased is selected, the following examination is generally carried out:
First, a purchaser (a wearer) is inquired about what kinds of eye diseases or other diseases the purchaser has suffered in the lifetime. Then, the purchaser is examined about whether the eye or eyes is or are normal, for example, the anterior eye (e.g., cornea or anterior sac) or the external eye (e.g., conjunctiva or eyelid) does not have injury or inflammation, whether the position of the crystalline lens is normal, whether the crystalline lens is not turbid, whether the eyeground is normal, whether the amount of lacrimal fluid is appropriate, and so on. In addition, in order to select a contact lens that fits the eye of the wearer and ensures a high visual acuity of the eye, a corneal curve and a visual acuity of the wearer's eye are measured to determine a base curve, a diopter, etc. of a contact lens that are suitable for the wearer's eye.
Finally, while the thus obtained examination results and a type of a contact lens (e.g., a soft, hard, or disposable contact lens) that is desired or designated by the purchaser are taken into consideration, a contact lens suitable for the wearer is selected (this method is disclosed by, e.g., the home page of Menicon Co., Ltd., see “How Your Contact Lenses Are Selected”, retrieved online on Aug. 23, 2002; the Internet <URL: http://www.menicon.co.jp/first/lens.html>). When the contact lens is selected in this way, a care system therefor is additionally selected. The care system includes a lens care solution that is suitable for the material of the contact lens and can effectively remove dirt, etc. adhered to the lens so that the lens can be used in a better condition for a longer time, and additionally includes a method of caring the lens with the solution.
Meanwhile, recently, there has been proposed a contact lens that contains an organic-silicone component (a silicon-containing component) at a high proportion, for the purpose of having a sufficiently high oxygen permeability in view of safety to the eye. A Dk value (oxygen permeability coefficient) of this contact lens is effectively increased as the proportion of the organic-silicone component is increased. On the other hand, to this contact lens, a dirt component such as protein or lipid present in the lacrimal fluid of the eye easily adheres. Usually, the dirt component can be removed by an appropriately selected care system. However, in the case where this contact lens is worn by a wearer whose lacrimal fluid contains a more dirt component, the dirt component more easily adheres to the surfaces and inner portions of the lens. In this case, the dirt component cannot be sufficiently removed by a common care system. Thus, because of the adhesion and deposition of the dirt component, various problems such as worsening in the feel during wearing, lowering in the oxygen permeability of the lens, shortening in the lens life, lowering in the visual acuity, or corneal injury may occur at a high probability. That is, it is not recommended that the contact lens be worn by the wearer.
However, the conventional contact-lens selecting method is for inspecting only whether a contact lens fits the eye of a wearer or how the contact lens is felt by the wearer. Therefore, whether dirt is likely to adhere to the contact lens when the lens is worn by the wearer, that is, whether the above-described problems are likely to occur is not inspected till, after the wearer purchases and uses the lens, the purchaser feels subjective symptoms such as fogging of the lens or congestion of the eye and accordingly the lens is examined. Thus, there have been many cases where a contact lens and a care system that are not suitable for a wearer are selected.